FIELD EVALUATION OF SESAME GERMPLASM AGAINST SESAME PHYLLODY DISEASE

Abstract

Phyllody disease, caused by phytoplasma, is a major threat for the successful production of sesame worldwide, including Pakistan. Use of resistant varieties is considered as an economical and durable method of controlling this malady. Therefore, the resistance of 133 sesame genotypes belonging to different regions was evaluated in the field under high inoculum pressure for two consecutive years. During the first year (2007), three genotypes namely NS 98002-04, NS 98003- 04 and NS 99005-01 were ranked as highly resistant as they remained symptomless till the harvest of crop while eleven others namely; NS97001-04, NS01004-04, Sumboonkkae, NS940051-04, NS20005-04, NS 11704, NS96019-04, Ahnsankkac, NS 11504, Hansumkkae and NS99006-04 were scored as resistant with percent disease infection (PDI) of 3.12, 3.33, 3.40, 3.45, 5.0, 5.30, 5.88, 7.14, 8.69, 8.70 and 10%, respectively. Other genotypes ranked between moderately resistant to highly susceptible with PDI values ranging from 10.71% to 65.12%. During second year all the tested genotypes were found to be infected with phyllody disease. However, four genotypes viz., NS98002-04, NS98003-04, NS99005-01 and NS01004-04 were resistant with PDIs of 3.25, 3.25, 3.75 and 10.0% respectively. Combined analysis of data also showed that these genotypes could be considered as promising for breeding programmes.